Synergistic herbicidal compositions

ABSTRACT

Synergistic herbicidal activity is displayed by composition comprising the following two components: 
     (a) a pyrrolidone of the formula ##STR1##  in which X is selected from the group consisting of hydrogen, chlorine, and methyl; Y is selected from the group consisting of hydrogen, chlorine, and bromine; Z is selected from the group consisting of chlorine and bromine; R 1  is selected from the group consisting of hydrogen and C 1  -C 4  alkyl; R 2  is selected from the group consisting of hydrogen, C 1  -C 4  alkyl, acetyl, trifluoromethyl, nitro, cyano, C 1  -C 4  alkoxy, C 1  -C 4  alkylthio, C 1  -C 4  alkylsulfinyl, C 1  -C 4  alkylsulfonyl, trifluoromethylthio, trifluoromethylsulfinyl, trifluoromethylsulfonyl, pentafluoropropionamido, and 3-methylureido; and R 3  is selected from the group consisting of hydrogen, C 1  -C 4  alkyl, chlorine and trifluoromethyl; and 
     (b) a cyclohexenedione of the formula ##STR2##  in which R 4  is 1&#39;-(2-hydroxyethylimino)ethyl or acetyl, at a weight ratio of (a) to (b) of from about 0.01:1 to about 10:1.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of application Ser. No. 086,972, filed Oct. 22, 1979, now abandoned.

BACKGROUND OF THE INVENTION

The protection of crops from weeds and other vegetation which inhibit crop growth by consuming valuable acreage or soil nutrients is a constantly recurring problem in agriculture. To help combat this problem, researchers in the field of synthetic chemistry have produced an extensive variety of chemicals and chemical formulations effective in the control of such unwanted growth. Chemical herbicides of many types have been disclosed in the literature and a large number are in commercial use.

In many cases, active herbicides have been shown to be more effective in combination than when applied individually. The result is often termed "synergism", since the combination demonstrates a potency or activity level exceeding that which it would be expected to have, based on a knowledge of the individual potencies of the components. The present invention resides in the discovery that certain pyrrolidones and certain cyclohexenediones, already known individually for their herbicidal potency, display this synergistic effect when applied in combination.

PRIOR ART

The two classes of compounds forming the combination which is the subject of the present invention are independently known in the art as active herbicides. Pyrrolidones are disclosed as herbicides in U.S. Pat. No. 4,110,105 (Teach, Aug. 29, 1979), and cyclohexenediones are similarly disclosed in the commonly assigned co-pending applications Ser. No. 947,217 and Ser. No. 947,218, both filed on Sept. 29, 1978.

DESCRIPTION OF THE INVENTION

It has now been discovered that synergism in the control of undesirable vegetation is exhibited by compositions comprising a mixture of the following two components:

(a) a pyrrolidone of the formula ##STR3## in which

X is selected from the group consisting of hydrogen, chlorine and methyl;

Y is selected from the group consisting of hydrogen, chlorine and bromine;

Z is selected from the group consisting of chlorine and C₁ -C₄ alkyl;

R¹ is selected from the group consisting of hydrogen and C₁ -C₄ alkyl;

R² is selected from the group consisting of hydrogen, halogen, C₁ -C₄ alkyl, acetyl, trifluoromethyl, nitro, cyano, C₁ -C₄ alkoxy, C₁ -C₄ alkylthio, C₁ -C₄ alkylsulfinyl, C₁ -C₄ alkylsulfonyl, trifluoromethylthio, trifluoromethylsulfinyl, trifluoromethylsulfonyl, pentafluoropropionamido, and 3-methylureido; and

R³ is selected from the group consisting of hydrogen, C₁ -C₄ alkyl, chlorine and trifluoromethyl;

and

(b) a cyclohexenedione of the formula

in which R⁴ is 1'-(2-hydroxyethylimino)ethyl or acetyl.

The terms "alkyl," "alkoxy," "alkylthio," etc., as used herein include both straight-chain and branched-chain groups. All carbon atoms ranges are inclusive of upper and lower limits.

Examples of pyrrolidones useful in the present invention are:

1-phenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-phenyl-3,3-dichloro-4-chloromethyl-2-pyrrolidone

1-(2',6'-dimethylphenyl)-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-chlorophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-p-chlorophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-trifluoromethylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-phenyl-3-chloro-3-methyl-4-chloromethyl-2-pyrrolidone

1-(3',4'-dichlorophenyl)-3,3-dichloro-4-chloromethyl-2-pyrrolidone

1-m-trifluoromethylphenyl-3,3-dichloro-4-chloromethyl-2-pyrrolidone

1-m-trifluoromethylphenyl-3-chloro-4-methyl-4-chloromethyl-2-pyrrolidone

1-p-tolyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-fluorophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-trifluoromethyl-3-bromo-4-bromomethyl-2-pyrrolidone

1-(3',4'-dichlorophenyl)-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-pentafluoropropionamidophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

cis-1-m-trifluoromethylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

trans-1-m-trifluoromethylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-nitrophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-(3',5'-dichlorophenyl)-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-trifluoromethylphenyl-3-chloro-4-(1'-chloroethyl)-2-pyrrolidone

1-m-cyanophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-(3',5'-dichlorophenyl)-3,3-dichloro-4-chloromethyl-2-pyrrolidone

1-m-trifluoromethylphenyl-3,3-dichloro-4-(1'-chloroethyl)-2-pyrrolidone

1-m-cyanophenyl-3,3-dichloro-4-chloromethyl-2-pyrrolidone

1-(3'-trifluoromethyl-4'-chlorophenyl)-3-chloro-4-chloromethyl-2-pyrrolidone

1-(3'-trifluoromethyl-4'-chlorophenyl)-3,3-dichloro-4-chloromethyl-2-pyrrolidone

1-m-trifluoromethylthiophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-methylthiophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-trifluoromethylsulfinylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-methylsulfinylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-methylsulfonylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-trifluoromethylsulfonylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-(3',5'-bis-trifluoromethylphenyl)-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-methoxyphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-acetylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-tolyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-trifluoromethylphenyl-4-chloromethyl-2-pyrrolidone

1-m-bromophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-o-chlorophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-m-iodophenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-p-methoxyphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

1-o-trifluoromethylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone

These and other pyrrolidones within the scope of the invention can be prepared by the procedures described in U.S. Pat. No. 4,110,105.

In the compositions of the present invention, pyrrolidones of the following formula are preferred: ##STR4##

Cyclohexenediones included in the present invention are 2-1'-(2-hydroxyethylimino)ethyl-1-hydroxy-4,4,6,6,-tetramethyl cyclohexen-3,5-dione ##STR5## and 1-hydroxy-2-acetyl-4,4,6,6-tetramethyl cyclohexene-3,5-dione ##STR6##

The terms "synergism" and "synergistic" are used herein to convey the result observed when a combination of herbicides demonstrates a potency in excess of that which the combination would be expected to produce on the basis of the potencies of each herbicide applied individually.

The term "herbicide" is used herein to denote a compound which controls or modifies the growth of plants. The term "herbicidally effective amount" is used to indicate the quantity of such a compound or combination of such compounds which is capable of producing a controlling or modifying effect. Controlling or modifying effects include all deviations from natural development, for example: killing, retardation, defoliation, desiccation, regulation, stunting, tillering, stimulating, leaf burn, dwarfing and the like. The term "plants" is used to include germinating seeds, emerging seedlings and established vegetation, including roots and above-ground portions.

In the compositions of this invention, the pyrrolidone:cyclohexenedione weight ratio at which the herbicidal response is synergistic lies within the range of about 0.01:1 to about 10:1, preferably about 0.1:1 to about 5:1, most preferably about 0.1:1 to about 2:1.

Application rates will depend upon the weeds to be controlled and the degree of control desired. In general, the compositions of this invention are most efficiently employed at a rate of 0.01 to 50 pounds per acre (0.011 to 56 kilograms per hectare) of the active ingredients, preferably 0.1 to 25 pounds per acre (0.11 to 28 kilograms per hectare).

The following examples provide further illustrations demonstrating the synergistic herbicidal response of the present compositions.

EXAMPLE I

This example demonstrates the synergistic response of 1-m-trifluoromethylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone and 2-1'-(2-hydroxyethylimino)ethyl-1-hydroxy-4,4,6,6-tetramethyl cyclohexen-3,5-dione in combined postemergence application to a variety of weeds.

Fiber flats measuring 21.0×31.1×8.9 cm were filled to a depth of 5.0 cm with loamy sand soil, containing 50 parts per million (ppm) of the commercial fungicide cis-N[(trichloromethyl)thio]-4-cyclohexene-1,2-dicarboximide (Captan®) and 18-18-18 fertilizer (percentages of N--P₂ O₅ --K₂ O on a weight basis). Several rows were impressed across the width of each flat and each row was seeded with a single weed species. The weed species included were downy brome (Bromus tectorum), tartary buckwheat (Fagopyrum tataricum), wild oat (Avena fatua), foxtail (Setaria viridis), and annual ryegrass (Lolium multiflorum). Ample seeds were planted to give about 20 to 50 seedlings per row after emergence depending on the size of the plants. The flats were then placed in a greenhouse for two weeks, where they were watered regularly.

At the end of this period, the foliage on the emergent weeds was sprayed with aqueous solutions of the test compounds. The quantities sprayed were such that the amount of each test compound applied per flat corresponded to the desired application rate in pounds per acre. In control flats, the test compounds were applied alone at various application rates, whereas in the test flats, solutions containing both compounds were applied. Additional flats not treated at all were used as a standard for measuring the extent of weed control occurring in the treated flats.

Two weeks after treatment, the control and test flats were compared to the standard and each row was rated visually in terms of percent control ranging from 0% to 100%, with 0% representing the same degree of growth as the same row in the standard and 100% representing complete kill of all weeds in the row. All types of plant injury were taken into consideration.

The results of these tests are listed in Table I in the columns headed by the symbol "0" (indicating the "observed" results). These results are compared with the expected results, shown in the columns headed by the symbol "E", derived from the control data using Limpel's formula (Limpel et al., 1962, "Weed Control by Dimethylchloroterephthalate Alone and in Certain Combinations," Procc. NEWCC., Vol. 16, pp 48-53): ##EQU1## where

X=observed percent injury when one of the herbicides is used alone, and

Y=observed percent injury when the other herbicide is used alone.

An asterisk (*) is used to indicate the tests where the results shown synergism, i.e., where the observed result exceeds the expected result. It is clear from the table that synergism was observed at many of the application rates tested.

                                      TABLE I                                      __________________________________________________________________________     HERBICIDE SYNERGISM TEST RESULTS                                               Test Compounds:                                                                 ##STR7##                                                                                Applied Postemergence                                                          Percent Control - O: Observed E: Expected                                                        Tartary                                            Application                                                                              Downy Rye-  Wild  Buck-                                              Rates (lb/A)                                                                             brome grass Oat   wheat Foxtail                                      A    B    O  E  O  E  O  E  O  E  O  E                                         __________________________________________________________________________     Control Data:                                                                  0.0625                                                                              --    30    0     0    10     0                                           0.125                                                                               --    70    60    0    60     20                                          0.25 --    90    80    40   95     90                                          --   0.0625                                                                               0     0     0     0     0                                           --   0.125                                                                                0     0     0     0     0                                           --   0.25  0     30    20    0     0                                           Test Data:                                                                     0.0625                                                                              0.0625                                                                               0 30  0 0   0 0   0 10  0 0                                         0.0625                                                                              0.125                                                                                0 30  20*                                                                              0   0 0   0 10  10*                                                                              0                                         0.0625                                                                              0.25  0 30  40*                                                                              30  0 20  0 10  30*                                                                              0                                         0.125                                                                               0.0625                                                                               0 70  20                                                                               60  0 0  50 60 100*                                                                              20                                        0.125                                                                               0.125                                                                                10                                                                               70  40                                                                               60  0 0  20 60  40*                                                                              20                                        0.125                                                                               0.25  30                                                                               70  65                                                                               72  0 20 30 60  30*                                                                              20                                        0.25 0.0625                                                                              100*                                                                              90 100*                                                                              80  40                                                                               40 95 95  90                                                                               90                                        0.25 0.125                                                                               100*                                                                              90 100*                                                                              80  40                                                                               40 98*                                                                               95 100*                                                                              90                                        0.25 0.25 100*                                                                              90 100*                                                                              86 100*                                                                              52 98*                                                                               95  95*                                                                              90                                        __________________________________________________________________________      *Synergistic effect shown.                                               

EXAMPLE II

This example demonstrates the synergistic response of the same herbicides used in Example I at higher application rates. Fiber flats measuring 14.6×25.4×7.0 cm were used, and the weed species included annual ryegrass, wild oat and foxtail as in Example I, plus mustard (Brassica juncea). The weed foliage was sprayed with the test solutions two weeks after the seeds were planted, and injury ratings were taken three weeks later.

The results are shown in Table II, with synergism evident.

                  TABLE II                                                         ______________________________________                                         HERBICIDE SYNERGISM TEST RESULTS                                               TEST COMPOUNDS:                                                                 ##STR8##                                                                       ##STR9##                                                                              Applied Postemergence                                                          Percent Control - O: Observed E: Expected                              Application                                                                              Rye-               Wild                                              Rates (lb/A)                                                                             grass    Mustard   Oat     Foxtail                                   A     B       O      E   O     E   O    E    O    E                            ______________________________________                                         Control Data:                                                                  0.125 --       0       100        0      10                                    0.25  --       0       100        0      20                                    0.5   --       0       100        20     30                                    --     0.25    0       65         20      0                                    --    0.5      0       100        40      0                                    --    1.0      0       100        60      0                                    Test Data:                                                                     0.125 0.25     0     0            20  20    0   10                             0.125 0.5      0     0            60* 40    0   10                             0.125 1.0      0     0            75* 60    0   10                             0.25  0.25     0     0            85* 20    0   20                             0.25  0.5      0     0            90* 40    0   20                             0.25  1.0      0     0            98* 60    0   20                             0.5   0.25    20*    0           100* 36   30   30                             0.5   0.5     25*    0           100* 52   35*  30                             0.5   1.0     30*    0           100* 68   40*  30                             ______________________________________                                          *Synergistic effect shown.                                                     Blank spaces indicate 100% control in both observed and expected results,      precluding evaluation of synergism.                                      

EXAMPLE III

This example demonstrates synergistic herbicidal activity in pre-emergence surface application of the same herbicides used in Examples I and II. Fiber flats measuring 14.6×25.4×7.0 cm were seeded with foxtail, annual ryegrass, wild oat, and mustard as used in Examples I and II, as well as black grass (Alopecurus myosuroides). After seeding, the flats were sprayed the same day with the test solutions and injury ratings were taken three weeks and three days later.

The results are shown in Table III, where synergism is highly evident.

                                      TABLE III                                    __________________________________________________________________________     HERBICIDE SYNERGISM TEST RESULTS                                               TEST COMPOUNDS:                                                                 ##STR10##                                                                               Applies Pre-emergence                                                          Percent Control - O: Observed E: Expected                            Application                                                                              Black       Rye-  Wild                                               Rates (lb/A)                                                                             grass Foxtail                                                                              grass Oat   Mustard                                      A    B    O  E  O   E O  E  O  E  O   E                                        __________________________________________________________________________     Control Data:                                                                  0.25 --    30   100    40    10   100                                          0.5  --    60   100    70    30   100                                          0.75 --    95   100    75    40   100                                          --   1.0   0    0      0     10   0                                            --   1.5   0    0      0     15   0                                            --   2.0   0    0      0     20   0                                            Test Data:                                                                     0.25 1.0   60*                                                                              30        65*                                                                              40  30*                                                                              19                                              0.25 1.5   65*                                                                              30        70*                                                                              40  60*                                                                              24                                              0.25 2.0   85*                                                                              30        80*                                                                              40  75*                                                                              28                                              0.5  1.0   85*                                                                              60       100*                                                                              70  75*                                                                              37                                              0.5  1.5   98*                                                                              60       100*                                                                              70  65*                                                                              41                                              0.5  2.0   98*                                                                              60       100*                                                                              70  98*                                                                              44                                              0.75 1.0   98*                                                                              95       100*                                                                              75 100*                                                                              46                                              0.75 1.5  100*                                                                              95       100*                                                                              75 100*                                                                              49                                              0.75 2.0  100*                                                                              95       100*                                                                              75 100*                                                                              52                                              __________________________________________________________________________      *Synergistic effect shown.                                                     Blank spaces indicate 100% control in both observed and expected results,      precluding evaluation of synergism.                                      

EXAMPLE IV

This example demonstrates the synergistic effect of 1-m-trifluoromethylphenyl-3-chloro-4-chloromethyl-2-pyrrolidone and 1-hydroxy-2-acetyl-4,4,6,6-tetramethyl cyclohexen-3,5-dione in combined postemergence application. Fiber flats measuring 14.6×25.4×7.0 cm were used, and the weed species included annual ryegrass, wild oat, foxtail, and mustard as in Example II. The weed foliage was sprayed with the test solutions two weeks after the seeds were planted, and injury ratings were taken three weeks later.

The results are shown in Table IV, where synergism is highly evident.

                  TABLE IV                                                         ______________________________________                                         HERBICIDE SYNERGISM TEST RESULTS                                               TEST COMPOUNDS:                                                                 ##STR11##                                                                             Applied Postemergence                                                          Percent Control - O: Observed E: Expected                              Application                                                                              Rye-               Wild                                              Rates (lb/A)                                                                             grass    Mustard   Oat     Foxtail                                   A     B       O      E   O     E   O    E    O    E                            ______________________________________                                         Control Data:                                                                  0.125 --       0       100        0      10                                    0.25  --       0       100        0      20                                    0.5   --       0       100       20      30                                    --    0.25     0       100       20        0                                   --    0.5      0       100       30       0                                    Test Data:                                                                     0.125 0.25     0     0           20   20   10   10                             0.125 0.5     20*    0           40*  30   40*  10                             0.25  0.25    10*    0           40*  20   20   20                             0.25  0.5     10*    0           60*  30   60*  20                             0.5   0.25    20*    0           40*  36   40*  30                             0.5   0.5     60*    0           65*  44   60*  30                             ______________________________________                                          *Synergistic effect shown.                                                     Blank spaces indicate 100% control in both observed and expected results,      precluding evaluation of synergism.                                      

The compositions of this invention are useful as herbicides demonstrating synergistic activity for the control of undesirable vegetation. The compositions can be formulated in the same manner in which herbicides are generally formulated. The compounds may be applied either separately or combined as part of a two-part herbicidal system.

The object of the formulation is to apply the compositions to the locus where control is desired by a convenient method. The "locus" is intended to include soil, seeds, and seedlings, as well as established vegetation.

Formulations will generally contain several additives. Among these are some inert ingredients and diluent carriers such as organic solvents, water, oil and water, water in oil emulsions, carriers of dust and granules, and surface active, wetting, dispersing, and emulsifing agents.

Fertilizers, such as ammonium nitrate, urea and superphosphates may also be added.

Aids to rooting and growth, such as compost, manure, humus, sand, etc., may likewise be added.

The formulations are commonly dusts, wettable powders, granules, solutions or emulsifiable concentrates.

Dusts are free-flowing powder compositions containing the herbicidal compound impregnated on a particulate carrier. The particle size of the carrier is usually in the approximate range of 30 to 50 microns. Examples of suitable carriers are talc, bentonite, diatomaceous earth, and pyrophyllite. Anticaking and antistatic agents can be added, if desired. The composition generally contains up to 50% of active ingredient. Dusts, like liquid compositions can be applied from boom and hand or powder sprayers or airplanes.

Wettable powders are finely divided compositions comprising a particulate carrier impregnated with the herbicidal compound and additionally containing one or more surface active agents. The surface active agent promotes rapid dispersion of the powder in aqueous medium to form stable, sprayable suspensions. A wide variety of surface active agents can be used, for example, long chain fatty alcohols; salts of sulfonic acid; esters of long chain fatty acids; and polyhydric alcohols, in which the alcohol groups are free, omega-substituted polyethylene glycols of relatively long chain length.

Granules comprise the herbicidal composition impregnated on a particulate inert carrier having a particle size of about 1 to 2 millimeters in diameter. The granules can be made by spraying a solution of the active ingredient in a volatile solvent onto the granular carrier. Suitable carriers in preparation of granules include clay, vermiculite, sawdust, granular carbon, etc.

The herbicidal compositions can also be applied to the soil in the form of a solution in a suitable solvent. Solvents frequently used in herbicidal formulations include kerosene, fuel oil, xylene, petroleum fractions with boiling ranges above xylene, and aromatic petroleum fractions rich in methylated naphthalenes.

Emulsifiable concentrates consist of an oil solution of the herbicide along with an emulsifying agent. Prior to use the concentrate is diluted with water to form a suspended emulsion of oil droplets. The emulsifiers used are usually a mixture of anionic and nonionic surfactants. Other additives such as spreading agents and stickers can be included in the emulsifiable concentrate.

It is not necessary that the compositions be admixed with the soil particles. After application by the above discussed methods, they may be distributed below the soil surface to a depth of at least one-half inch by conventional means such as discing, dragging, or mixing. 

What is claimed is:
 1. A synergistic herbicidal composition consisting essentially of a mixture of(a) an effective amount of a pyrrolidone of the formula ##STR12## and (b) an effective amount of a cyclohexenedione of the formula ##STR13## in which R⁴ is 1'-(2-hydroxyethylimino)ethyl, at a weight ratio of (a) to (b) of from about 0.1:1 to about 5:1.
 2. A composition according to claim 1 in which the weight ratio of (a) to (b) is from about 0.1:1 to about 2:1.
 3. A composition according to claim 1 in which the --CF₃ on the pyrrolidone is in the 3-position.
 4. A method of controlling undesirable vegetation which comprises applying to the locus where control is desired a herbicidal composition consisting essentially of a mixture of(a) an effective amount of a pyrrolidone of the formula ##STR14## and (b) an effective amount of a cyclohexenedione of the formula ##STR15## in which R⁴ is 1'-(2-hydroxyethylimino)ethyl, at a weight ratio of (a) to (b) of from about 0.1:1 to about 5:1.
 5. A method according to claim 4 in which the weight ratio of (a) to (b) is from about 0.1:1 to about 2:1.
 6. A method according to claim 4 in which the --CF₃ on the pyrrolidone is in the 3-position. 